<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <style type="text/css">
        .box1{
            width: 100px;
            height: 100px;
            background-color: #bfa;
        }
        h1{
            width: 500px;
            height: 300px;
            text-align: center;
            line-height: 300px;
            background-color: aqua;
            color: yellow;
            font-size: 100px;
        }
        #box2{
            width: 100px;
            height: 100px;
            background-color: #bfa;
            text-align: center;
            line-height: 100px;
            font-size: 16px;
            color: red;
        }
    </style>
</head>
<body>

<div class="box1">你好</div>
<h1>nihao</h1>
<div id="box2">nihao</div>

</body>
</html>